668 research outputs found

    A Racial Reckoning: Anti-Asian racism and exclusion in higher education

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    The Atlanta massacre on March 16, 2021, spurred a series of solidarity statements with the broader Asian and Asian American1 community from higher education institutions across the nation. While many colleges and universities have expressed their grief and support with the larger Asian and Asian American community, the same institutions have yet to reflect and reckon with their own history of exclusion, which has omitted Asian and Asian American students from larger conversations of diversity, equity, and inclusion. The purposes of this brief are to name the forms of anti-Asian racism that already exist in higher education institutions and to propose a series of recommendations to address the foreseeable forms of overt and covert anti-Asian violence that may occur when students return to campuses in fall 2021 and beyond. We recommend that institutions of higher education: create effectual task forces to think strategically about racism and xenophobia towards Asian and Asian American students; increase funding for ethnic studies, specifically, Asian American Studies Departments, Programs, and Centers; and collect and report disaggregated data on diverse subgroups of Asian and Asian American students

    Anti-Asian Bullying and Harassment: Symptoms of racism in K-12 schools during COVID-19

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    The COVID-19 pandemic has posed many challenges for K-12 students. However, these challenges have not been experienced equally across student groups. There has been a significant increase in mainstream media coverage of anti-Asian racism, but very little attention has been given to Asian American youth, who are not immune from incidents of bullying and harassment in our K-12 schools. This brief discusses how Asian American and Pacific Islander (AAPI)1 students face unique challenges associated with bullying and harassment because of their racial and ethnic identity. We examine the historical context of bullying and harassment of Asian Americans and how that persists as anti-Asian racism today. Finally, we propose policy solutions to create a more positive learning environment and address racist attitudes towards this specific community. Notably, we propose that K-12 leaders disaggregate data by ethnic subgroup, collect more comprehensive data on school bullying, harassment, and victimization disaggregated by AAPI ethnic subgroups, and invest in culturally sustaining mental health resources and curriculum

    Transient response of a quantum wave to an instantaneous potential step switching

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    The transient response of a stationary state of a quantum particle in a step potential to an instantaneous change in the step height (a simplified model for a sudden bias switch in an electronic semiconductor device) is solved exactly by means of a semianalytical expression. The characteristic times for the transient process up to the new stationary state are identified. A comparison is made between the exact results and an approximate method.Comment: 8 pages, 8 figures, Revtex

    Landau-Zener-Stueckelberg effect in a model of interacting tunneling systems

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    The Landau-Zener-Stueckelberg (LZS) effect in a model system of interacting tunneling particles is studied numerically and analytically. Each of N tunneling particles interacts with each of the others with the same coupling J. This problem maps onto that of the LZS effect for a large spin S=N/2. The mean-field limit N=>\infty corresponds to the classical limit S=>\infty for the effective spin. It is shown that the ferromagnetic coupling J>0 tends to suppress the LZS transitions. For N=>\infty there is a critical value of J above which the staying probability P does not go to zero in the slow sweep limit, unlike the standard LZS effect. In the same limit for J>0 LZS transitions are boosted and P=0 for a set of finite values of the sweep rate. Various limiting cases such as strong and weak interaction, slow and fast sweep are considered analytically. It is shown that the mean-field approach works well for arbitrary N if the interaction J is weak.Comment: 13 PR pages, 15 Fig

    Time scale of forerunners in quantum tunneling

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    The forerunners preceding the main tunneling signal of the wave created by a source with a sharp onset or by a quantum shutter, have been generally associated with over-the-barrier (non-tunneling) components. We demonstrate that, while this association is true for distances which are larger than the penetration lenght, for smaller distances the forerunner is dominated by under-the-barrier components. We find that its characteristic arrival time is inversely proportional to the difference between the barrier energy and the incidence energy, a tunneling time scale different from both the phase time and the B\"uttiker-Landauer (BL) time.Comment: Revtex4, 14 eps figure

    Time dependence of evanescent quantum waves

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    The time dependence of quantum evanescent waves generated by a point source with an infinite or a limited frequency band is analyzed. The evanescent wave is characterized by a forerunner (transient) related to the precise way the source is switched on. It is followed by an asymptotic, monochromatic wave which at long times reveals the oscillation frequency of the source. For a source with a sharp onset the forerunner is exponentially larger than the monochromatic solution and a transition from the transient regime to the asymtotic regime occurs only at asymptotically large times. In this case, the traversal time for tunneling plays already a role only in the transient regime. To enhance the monochromatic solution compared to the forerunner we investigate (a) frequency band limited sources and (b) the short time Fourier analysis (the spectrogram) corresponding to a detector which is frequency band limited. Neither of these two methods leads to a precise determination of the traversal time. However, if they are limited to determine the traversal time only with a precision of the traversal time itself both methods are successful: In this case the transient behavior of the evanescent waves is at a time of the order of the traversal time followed by a monochromatic wave which reveals the frequency of the source.Comment: 16 text pages and 9 postscript figure

    Anonymous Single-Sign-On for n designated services with traceability

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    Anonymous Single-Sign-On authentication schemes have been proposed to allow users to access a service protected by a verifier without revealing their identity which has become more important due to the introduction of strong privacy regulations. In this paper we describe a new approach whereby anonymous authentication to different verifiers is achieved via authorisation tags and pseudonyms. The particular innovation of our scheme is authentication can only occur between a user and its designated verifier for a service, and the verification cannot be performed by any other verifier. The benefit of this authentication approach is that it prevents information leakage of a user's service access information, even if the verifiers for these services collude which each other. Our scheme also supports a trusted third party who is authorised to de-anonymise the user and reveal her whole services access information if required. Furthermore, our scheme is lightweight because it does not rely on attribute or policy-based signature schemes to enable access to multiple services. The scheme's security model is given together with a security proof, an implementation and a performance evaluation.Comment: 3

    Search for low lying dipole strength in the neutron rich nucleus 26^{26}Ne

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    Coulomb excitation of the exotic neutron-rich nucleus 26^{26}Ne on a nat^{nat}Pb target was measured at 58 A.MeV in order to search for low-lying E1 strength above the neutron emission threshold. Data were also taken on an nat^{nat}Al target to estimate the nuclear contribution. The radioactive beam was produced by fragmentation of a 95 A.MeV 40^{40}Ar beam delivered by the RIKEN Research Facility. The set-up included a NaI gamma-ray array, a charged fragment hodoscope and a neutron wall. Using the invariant mass method in the 25^{25}Ne+n channel, we observe a sizable amount of E1 strength between 6 and 10 MeV. The reconstructed 26^{26}Ne angular distribution confirms its E1 nature. A reduced dipole transition probability of B(E1)=0.49±\pm0.16 e2fm2e^2fm^2 is deduced. For the first time, the decay pattern of low-lying strength in a neutron-rich nucleus is obtained. The results are discussed in terms of a pygmy resonance centered around 9 MeV

    Structural evolution in the neutron-rich nuclei 106Zr and 108Zr

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    The low-lying states in 106Zr and 108Zr have been investigated by means of {\beta}-{\gamma} and isomer spectroscopy at the RI beam factory, respectively. A new isomer with a half-life of 620\pm150 ns has been identified in 108Zr. For the sequence of even-even Zr isotopes, the excitation energies of the first 2+ states reach a minimum at N = 64 and gradually increase as the neutron number increases up to N = 68, suggesting a deformed sub-shell closure at N = 64. The deformed ground state of 108Zr indicates that a spherical sub-shell gap predicted at N = 70 is not large enough to change the ground state of 108Zr to the spherical shape. The possibility of a tetrahedral shape isomer in 108Zr is also discussed.Comment: 10 pages, 3 figures, Accepted for publication in Phys. Rev. Let

    A Measurement of the Coulomb Dissociation of 8B at 254 MeV/nucleon and the 8B Solar Neutrino Flux

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    We have measured the Coulomb dissociation of 8B into 7Be and proton at 254 MeV/nucleon using a large-acceptance focusing spectrometer. The astrophysical S17 factor for the 7Be(p,gamma)8B reaction at E{c.m.} = 0.25-2.78 MeV is deduced yielding S17(0)=20.6 \pm 1.2 (exp.) \pm 1.0 (theo.) eV-b. This result agrees with the presently adopted zero-energy S17 factor obtained in direct-reaction measurements and with the results of other Coulomb-dissociation studies performed at 46.5 and 51.2 MeV/nucleon.Comment: paper to be published in Phys. Rev. Lett. 3 figures. New Version fixes formatting problems with the figures only. There are no other change
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